The invention concerns orthotic devices for applying forces or pressures at the joints of the human body and more particularly for applying traction and other manipulative forces at the digits of the extremities, especially the hands. Devices called "lively" splints may be included in this group.
Certain non-malignant conditions, such as arthritis and the like, cause unnatural pull on the tendons and muscles of the hand and result in painful joints, deformity and sometimes partial or total loss of use of the hand. Pain may be experienced because a phalanx is pulled out of normal position in relation to another phalanx or the metacarpal bone, causing the respective joint to move out of normal position. Or the digital bones or phalanxes of a digit may become displaced with respect to each other as a result of unnatural pull on or displacement of the tendons and muscles resulting in a misalignment or distortion of the digit.
Devices which apply an axial force (traction) across a joint, or opposing lateral forces on opposite sides of a joint, tend to return the joint to a more normal configuration and relieve pain. A number of devices of this general type are known, but while they may function satisfactorily they suffer from variety of limitations. Most of them are single purpose, providing only one function, and individual units may require custom fitting to particular digits or to the extremity as a whole and may not be readily adaptable to another application. Some devices severely limit the mobility of individual digits or of the whole extremity. The net cost of using such devices may be relatively high, both because of the high cost of manufacture of a relatively complicated design and the duplication required because of lack of adaptability of the design. For example, the devices disclosed in U.S. Pat Nos. 3,533,405, Collins, 3,595,225 Beeman and 4,220,334 Kanamoto all have a single purpose or mode of application. Certainly no device is known which provides two or more functions from a group of functions comprising: applying traction; applying opposing lateral forces at a joint; and applying separating forces between two digits. No simple device is known for applying traction at an individual interphalangeal joint of a digit.